The subject matter of the disclosed invention relates generally to dental cleaning, abrading, etching, and cutting processes and apparatus. Prior art has instructed that dental cleaning may be accomplished through ultrasonic and mechanical sandblasting processes. Mixtures of high pressure fluids, including both liquids and gases, with abrasive particles, such as sand, are described in U.S. Pat. No. 2,133,149, Poncelet; U.S. Pat. No. 2,577,465, Jones; U.S. Pat. No. 2,744,361, Larson; and U.S. Pat. No. 4,369,607, Bruggeman et al. The referenced patents provide for a means to deliver a high pressure liquid stream mixed with large non-soluble abrasive particles delivered to a surface for cleaning or abrading.
Recently, the mixture of high pressure streams of liquid and abrasive for cleaning teeth has been envisioned. In U.S. Pat. No. 4,412,402, Gallant, an apparatus is disclosed which provides separate nozzles for ejection of a water stream and abrasive laden gas stream mixed at a point in the space between the nozzle orifice and the cleaning surface. One limitation of Gallant is that the distance between the apparatus and the cleaning surface must be carefully monitored so as to ensure proper mixture of the streams. Secondly, use of the Gallant apparatus suggests that abrasive particles not enveloped by the stream of liquid can be inhaled by a dental patient. In U.S. Pat. No. 4,595,365, Edel et al., the inventors have provided a means to mix a high pressure liquid stream and an abrasive in a way which overcomes some of the limitations of Gallant. Use of the apparatus disclosed in Edel still indicates that incomplete mixing of the liquid and abrasive particles occurs allowing airborne particles to be inhaled by a patient.
The apparatus disclosed in Gallant and Edel et al. both utilize pressurized air streams as a means to propel abrasive material toward the cleaning surface and a curtain of water. Deflection of the stream of water off the cleaning surface will result in both the dentist and the patient being splattered with the abrasive laden liquid. The deflected liquid is both a nuisance to the dentist and offensive to the patient.
Current sandblasters are limited as to the size of abrasive particles that may be used. Cracks, pits or fissures in dental and other surfaces may be smaller than the size of abrasive particles currently used in other sandblasters. This size limitation may result in incomplete cleaning or inadequate surface preparation for adhesive bonding procedures. Particles smaller than 20 microns can generally not be used effectively in existing sandblasters because of clumping due to moisture effects or because of static electrical charges which inhibit the flow of particles.